||These new STIS FUVMAMA PHOTTAB reference files contain updated sensitivity curves for all postSM4 E140M observations. The E140M grating started showing evidence of blaze function shape changes in 2012, that over time resulted in relative flux calibration errors outside of specifications in the STIS IHB. These files include new derivations of the E140M throughput curves from observations of G191B2B and new derivations of the blaze function shift coefficients from monitoring observations of BD 28D4211. New E140M ripple tables were also derived and are being delivered concurrently.
The new STIS FUVMAMA RIPTAB files contain updated, normalized sensitivity curves for postSM4 E140M observations. The E140M grating started showing evidence of blaze function shape changes in 2012, that over time resulted in relative flux calibration errors outside of specifications in the STIS IHB. The derivation of new sensitivity curves for the PHOTTABs required the creation of new, self-consistent ripple functions to be delivered concurrently.
||The COS NUV TDSTAB was updated because the previous file, delivered in 2010, overestimated subsequent declines in sensitivity. This had the effect of overcorrecting recent spectra and giving flux errors outside the 5 percent tolerance. In the new file, slopes and intercepts were updated for all stripes of G185M, G225M, and G230L. Due to its sharply reduced sensitivity and lack of GO use since 2013, the parameters for G285M were not updated. Parameters were determined from fits to spectra obtained in the ongoing NUV Spectroscopic Sensitivity Monitor program. The August 2019 breakpoint present in previous NUV TDSTABs was removed.
||These files were generated following the ACS WFC anneal on July 20, 2020, and should be used to calibrate ACS WFC observations taken between June 26, 2020 and July 20, 2020.
||Throughout the lifetime of WFC3, a growing number of blobs small, circular regions with slightly decreased sensitivity have appeared in WFC3 IR images. These blobs appear due to particulates on the channel select mechanism CSM the movable mirror that is used to direct light into either the UVIS or IR channels of the instrument. These particulates are likely cracked epoxy originating from two pins joining the CSM motor shafts to the alignment bellows, therefore, it is critical that blob accumulation is monitored as a growing number of blobs may signify a loosening of these pins, and thus a defective CSM. Furthermore, the flagging of these blobs in the IR bad pixel table ensures that all of the blobs are masked in any science images where they may be present. More information can be found on WFC3 2018 06